Join Date: Jul 2010
Location: Outside Philadelphia, PA
If this is a new tank, with nothing living, you can fill it with tap water, and then add Prime and anything else you want to use.
However, what are you going to do when you want to do a 10 gal water change? Some methods of using ferts use a 50% water change per week.
I recommend you get yourself a container so that you can mix and age large quantities of water. You never know when you'll need to do that emergency water change.